Grille and method and apparatuses for manufacturing it

ABSTRACT

Technology for bending a tube through a desired curvature along its longitudinal axis while resisting buckling of the tube sidewalls. The technology, which has particular application for manufacturing grilles for motor vehicles, includes: a method of bending a tube through a desired curvature along its longitudinal axis; a tube having a desired curvature along its longitudinal axis made in accordance with this method; an apparatus for bending a tube having a predetermined cross-section through a desired curvature along its longitudinal axis; an apparatus for squaring a tube having a predetermined cross-section; an apparatus for reinforcing a portion of a tube during manufacturing; a stainless steel tube having a desired curvature along its longitudinal axis, a substantially polygonal cross-section, and a sidewall thickness in a range between one tenth of one millimeter and one millimeter; and finally a grille assembled from a plurality of such stainless steel tubes in spaced-apart disposition with means for connecting adjacent tubes together, including crosspieces connected to the tubes by conventional means, including welds, spot-welds, adhesive, or fasteners.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to curved tubular bars and methods andapparatuses for manufacturing them. More particularly, the inventionrelates to stainless steel curved tubular bars having thin sidewalls,and to methods and apparatuses for manufacturing them and assemblingthem into a grille, for example a radiator grille for a motor vehicle.

2. Description of Related Art

Bars, including tubular bars, have many applications in manufacturing,including use as parts in motor vehicles. When thoughtfully designed,bars that are tubular, instead of solid, can strike a useful balancebetween robustness on the one hand and amount of material, as measuredin weight and cost, on the other hand.

Radiator grilles are an illustrative application for such bars, andprovide interesting examples of past attempts to strike this balance inthe bars that function as grille slats. In this application, the barsneed to be robust but also light and inexpensive. Additionally, currentmarket tastes dictate that each slat should be an elongated prism,deeper than it is thick; all surfaces of the prism should be coatedblack except for the front surface, which should be polished metal. Theslats need not be linear, and in fact it is generally desirable thatsome portions follow a gentle curve along the horizontal plane.

Achieving the desired configuration poses certain technical challenges.First, the slat material should be robust and should hold a good polish,but it should also be light and easy to bend through the desired curves.Second, the slat should require a minimum number of manufacturing andassembly steps to keep production costs down.

One popular slat is formed as a simple aluminum extrusion that has allsurfaces painted black, except for the front surface, which is polished.Observations of the slat in use indicate that the polished front surfacedoes not stand up well to age or use; it nicks, oxidizes and discolors.

An improved slat is also formed as an aluminum extrusion that is paintedblack; however this slat also includes a polished stainless steel stripthat is affixed to the front surface of the extrusion. In some cases,the strip is affixed to the extrusion with only adhesive; in othercases, a key and channel coupling supplements the adhesive. Observationsof this slat in use indicate that the polished stainless steel stripholds its appearance better than the polished aluminum; however, thejoint between the strip and the extrusion seems to be a likely point offailure. Another disadvantage is that the slat requires two parts to bemanufactured and then assembled, increasing production costsaccordingly.

In considering the slats described above, it can be seen that stainlesssteel is a desirably robust material to use. Unfortunately, stainlesssteel is more difficult to bend through curves than aluminum and is tooheavy and expensive to use in solid bars. When a stainless steel tubularbar is bent, there is a tendency for its sidewalls to buckle eitherinward or outward, weakening the bar and ruining its appearance. Forthis reason, stainless steel slats currently available in themarketplace tend to be formed as small-diameter cylindrical tubes thatbetter resist such bending-induced buckling than do prismical tubes withtheir sharp edges. However, it seems that the marketplace has rejectedthese cylindrical slats because they don't produce the desiredappearance; their whole circumference is uniformly polished, no part iscoated black, and they are not deeper than they are thick.

Accordingly, there is a need for a way to manufacture a stainless steelprismical tube that can be bent through curves along its longitudinalaxis to form the desired slat, but without buckling the sidewalls.Although it can be difficult to bend an expensive and heavy solidstainless steel prism, a tubular stainless steel prism has the sameoutward appearance and enjoys similar robustness and polish with lessweight and less material cost, and without recourse to complicatedmanufacturing or assembly steps needed for hybrid solutions as describedabove.

SUMMARY OF THE INVENTION

The present invention is directed to a way to bend a tube withoutbuckling the tube walls.

According to one aspect of the invention, there is provided a method ofbending a tube through a desired curvature along its longitudinal axis.The method includes reinforcing a portion the tube with a core thatallows the portion to bend but that resists buckling of the tube wallsand then bending the reinforced portion of the tube. Reinforcing aportion of the tube includes inserting into the tube a longitudinallybendable core that resists transverse compression, whereby the coreredistributes transverse forces applied to the portion. The core may beremoved after bending the reinforced portion of the tube.

The core may be formed from granules, liquid, or a spring mechanism. Theends of the tube, or even just the portion, can be sealed to discouragethe core from coming out.

The method is well suited for use on tubes having a polygonalcross-section, including a quadrilateral, parallelogrammic orrectangular cross-section. The tube may be formed from metal, includingstainless steel, and may have sidewalls with a range of thicknesses,including the range between one tenth of one millimeter and onemillimeter. In particular, a sidewall thickness of one tenth of onemillimeter provides a good balance between robustness and the amount ofsteel used, as measured in weight and cost of material.

Bending the reinforced portion of the tube may be performed by rollingthe portion between rollers that define between them a path having thedesired curvature, including feeding the portion through a channeldefined between the rollers that is substantially congruent with theoutside perimeter of the portion.

This method of manufacture might also include squaring the tube, bywhich is meant at least one of squaring the cross-section of the portionand longitudinally untwisting the portion. Such squaring may beperformed by rolling the tube between rollers that define between them asubstantially straight path, including feeding the portion through achannel defined between the rollers that is substantially congruent withthe outside perimeter of the tube.

According to another aspect of the invention, there is provided a tubehaving a desired curvature along its longitudinal axis, made inaccordance with the method just described above.

According to another aspect of the invention, there is provided anapparatus for bending an elongated body having a predeterminedcross-section through a desired curvature along its longitudinal axis.The apparatus includes: a housing; and first, second, and third rollers,each roller respectively having an axis of rotation and a rollingsurface, the rollers being rotatably mounted on the housing such thattheir respective axes of rotation are substantially parallel and theirrespective rolling surfaces define between them a channel having thedesired curvature and a cross-section substantially congruent with thecross-section of the body.

According to another aspect of the invention, there is provided anapparatus for squaring an elongated body having a predeterminedcross-section. The apparatus includes: a housing; and first and secondrollers, each roller respectively having an axis of rotation and arolling surface, the rollers being rotatably mounted on the housing suchthat their respective axes of rotation are substantially parallel andtheir respective rolling surfaces define between them a channel having across-section substantially congruent with the cross-section of thebody.

According to yet another aspect of the invention, there is provided anapparatus for reinforcing a portion of a tube during manufacturing. Thisapparatus includes a core having an outer diameter substantially equalto the inner diameter of the tube that allows the portion to bend alongits longitudinal axis but that resists buckling of the sidewalls of theportion. The core itself may be bendable along its longitudinal axis andmay resists transverse compression, such that it is operable toredistribute transverse forces applied to the portion.

This core may be formed from a plurality of granules such as sand, avolume of liquid such as water or hydraulic oil, or a spring mechanismsuch as a coil spring that has an outside perimeter substantiallycongruent with the inside perimeter of the portion.

According to still another aspect of the invention, there is provided astainless steel tube having a desired curvature along its longitudinalaxis, a substantially polygonal cross-section, and a sidewall thicknessin a range between one tenth of one millimeter and one millimeter oreven the range between one tenth of one millimeter and five tenths ofone millimeter. A sidewall thickness of one tenth of one millimeter agood balance between robustness and the amount of steel used, asmeasured in weight and cost of material. The tube may be made of variousstainless steel alloys, including iron-chromium-nickel alloy 304.

According to another aspect of the invention, there is provided a grillehaving a plurality of stainless steel tubes as described in theparagraph immediately above, in spaced-apart disposition and means forconnecting adjacent tubes, including crosspieces connected to the tubesby conventional means, including welds, spot-welds, adhesive, orfasteners.

Further aspects and advantages of the present invention will becomeapparent upon considering the following drawings, description, andclaims.

DESCRIPTION OF THE INVENTION

The invention will be more fully understood from the following detaileddescription taken in conjunction with the accompanying drawing figures,in which like reference numerals designate like parts throughout thevarious figures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1: is a front isometric view a grille assembled from a pluralitytubular bars, in accordance with one aspect of the present invention;

FIG. 2: is a back isometric view of the grille of FIG. 1;

FIG. 3: is a back isometric view of the grille of FIG. 1, detailing anend portion of the tubular bars;

FIG. 4: is a plan view of the grille of FIG. 1;

FIG. 5: is a front elevational view of the grille of FIG. 1;

FIG. 6: is a back elevational view of the grille of FIG. 1;

FIG. 7: is a right elevational view of the grille of FIG. 1;

FIG. 8: is a front isometric view of one tubular bar of the grille ofFIG. 1, in accordance with another aspect of the present invention;

FIG. 9: is a back isometric view of the tubular bar of FIG. 8;

FIG. 10: is a back isometric view of the tubular bar of FIG. 8,detailing an end portion of the tubular bar;

FIG. 11: is a plan view of the tubular bar of FIG. 8;

FIG. 12: is a front elevational view of the tubular bar of FIG. 8;

FIG. 13: is a back elevational view of the tubular bar of FIG. 8;

FIG. 14: is a right elevational view of the tubular bar of FIG. 8;

FIG. 15: is a front elevational view of an apparatus for bending the endportion of the tubular bar of FIG. 10, in accordance with another aspectof the present invention;

FIG. 16: is a right elevational view of the bending apparatus of FIG.15;

FIG. 17: is a plan view of the bending apparatus of FIG. 15;

FIG. 18: is a front isometric view of the bending apparatus of FIG. 15;

FIG. 19: is a front isometric view of the bending apparatus of FIG. 15,sectioned along the line A-A to highlight a feed-path through theapparatus;

FIG. 20: is a front isometric view of the bending apparatus of FIG. 15the end portion of the tubular bar of FIG. 10 on the feed-path;

FIG. 21: is a front isometric view of the bending apparatus of FIG. 15with the end portion of the tubular bar of FIG. 10 on the feed-path,sectioned along the line B-B to highlight a reinforcing-core within theend portion of the tubular bar;

FIG. 22: is a front isometric view of the bending apparatus of FIG. 15with the end portion of the tubular bar of FIG. 10 on the feed-path,sectioned along the line B-B to highlight a granular reinforcing-corewithin the end portion of the tubular bar;

FIG. 23: is a front isometric view of the bending apparatus of FIG. 15the end portion of the tubular bar of FIG. 10 on the feed-path,sectioned along the line B-B to highlight a liquid reinforcing-corewithin the end portion of the tubular bar;

FIG. 24: is a front isometric view of the bending apparatus of FIG. 15the end portion of the tubular bar of FIG. 10 the feed-path, sectionedalong the line B-B to highlight a mechanically-sprung reinforcing-corewithin the end portion of the tubular bar;

FIG. 25: is a front isometric view of the bending apparatus of FIG. 15the end portion of the tubular bar of FIG. 10 on the feed-path, the endportion of the tubular bar having both ends sealed to contain thereinforcing core;

FIG. 26: is a front elevational view of an apparatus for squaring thetubular bar of FIG. 8, in accordance with another aspect of the presentinvention;

FIG. 27: is a right elevational view of the squaring apparatus of FIG.26;

FIG. 28: is a plan view of the squaring apparatus of FIG. 26;

FIG. 29: is a front isometric view of the squaring apparatus of FIG. 26;

FIG. 30: is a front isometric view of the squaring apparatus of FIG. 26,sectioned along the line C-C to highlight a feed-path through theapparatus;

FIG. 31: is a front isometric view of the squaring apparatus of FIG. 26with the end portion of the tubular bar of FIG. 10 on the feed-path;

FIG. 32: is a front isometric view of the squaring apparatus of FIG. 26with the end portion of the tubular bar of FIG. 10 on the feed-path,sectioned along the line D-D to highlight a reinforcing-core within theend portion of the tubular bar;

FIG. 33: is a front isometric view of the squaring apparatus of FIG. 26with the end portion of the tubular bar of FIG. 10 on the feed-path,sectioned along the line D-D to highlight a granular reinforcing-corewithin the end portion of the tubular bar;

FIG. 34: is a front isometric view of the squaring apparatus of FIG. 26with the end portion of the tubular bar of FIG. 10 on the feed-path,sectioned along the line D-D to highlight a liquid reinforcing-corewithin the end portion of the tubular bar;

FIG. 35: is a front isometric view of the squaring apparatus of FIG. 26with the end portion of the tubular bar of FIG. 10 on the feed-path,sectioned along the line D-D to highlight a mechanically-sprungreinforcing-core within the end portion of the tubular bar; and

FIG. 36: is a front isometric view of the squaring apparatus of FIG. 26with the end portion of the tubular bar of FIG. 10 on the feed-path, theend portion of the tubular bar having both ends sealed to contain thereinforcing core.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

(a) Structure

The invention will now be further illustrated by way of specificexemplary embodiments shown in the drawings and described in greaterdetail herein.

FIGS. 1 through 7 show a grille according to one aspect of the presentinvention, generally illustrated at 50. The grille 50 is an assembly ofspaced-apart tubular bars 52 held together by crosspieces 54. Acrosspiece 54 may engage a bar 52 by any conventional means, for examplea weld, a spot-weld, an adhesive, or a fastener.

With reference now to FIGS. 7-14, a representative bar 52 according toone aspect of the invention will be described in further detail. The bar52 may be formed from any suitably robust and ductile material,including metal, including stainless steel, includingiron-chromium-nickel alloy 304. The bar 52 may have any cross-sectionalperimeter, including a polygon, including a quadrilateral, including atrapezoid or a parallelogram, including a rectangle, including a square.To save weight and the cost of materials, the bar 52 is tubular, havingsidewalls 56 with a thickness in the range of between 0.1 millimeter to1 millimeter, although other ranges might be chosen to strike anappropriate balance of physical and economic characteristics desirablefor a particular application. Better cost and weight savings can beachieved by specifying sidewalls 56 with a thickness in the range ofbetween 0.1 millimeter to 0.5 millimeter. Even better savings can beachieved by specifying sidewalls 56 with a thickness of approximately0.1 millimeter. The two end portions 58 of the bar 52 may be left openfor drainage or sealed for protection. Each of the exterior surfaces 60of the bar 52 may be coated, for example painted, or polished. The bar52 may be curved along its longitudinal axis; as illustrated it has beenbent through a large radius of curvature RL proximate its middle portion62 and a small radius of curvature RS proximate each of its two endportions 58.

With reference now to FIGS. 15-25, a method and apparatus for bending aportion of the bar 52 will be described in further detail. It should beunderstood that the portion may be the whole bar 52. The samedescription applies to an apparatus for bending the bar 52 through thelarge radius of curvature RL and the small radius of curvature RS, butfor conciseness only the latter will be described. It should berecognized however that the two operations could be performed on twodifferent bending apparatuses or that the two operations could beperformed in succession on the same bending apparatus, with the bendingapparatus being reconfigured between performance of the two operations.

With reference first to FIGS. 15-19, a bending apparatus according toone aspect of the invention is generally illustrated at 70. The bendingapparatus 70 has a housing 72 on which are mounted three or more rollers74 with substantially parallel axes of rotation. Between them, the threerollers 74 define a feed-path 76 through a desired radius of curvature,in this case the small radius of curvature RS. The rollers 74 may definegrooves 78 for improved material handling and adjacent grooves 78 may inturn define between them a channel 80 having a cross-sectionsubstantially congruent with the cross-sectional perimeter of the bar52. This channel 80 acts to reinforce the bar 52 from the outside, tohelp prevent the cross-section of the bar 52 from skewing and preventthe sidewalls 56 from buckling during the bending operation.

With reference now to FIG. 20, an end portion 58 of the bar 52 can beseen positioned for bending within the bending apparatus 70.

With reference now to FIGS. 21-25, the inclusion of a reinforcing-core82 inside the bar 52 will now be described. FIGS. 21-24 show areinforcing-core 82 inserted within the end portion 58 of the bar 52.The reinforcing-core 82, which is bendable along its longitudinal axisbut otherwise substantially incompressible, permits the bendingapparatus 70 to bend the end portion 58 of the bar 52 through thedesired small radius of curvature RS, but helps to prevent thecross-section of the bar 52 from skewing and the sidewalls 56 frombuckling during the bending operation by opposing, redirecting anddistributing the transverse forces applied by the rollers 74.

As shown respectively in FIGS. 22, 23, and 24, the reinforcing-core 82may for example be formed as: a packed mechanical mixture of granules 84such as sand, a volume of liquid 86 such as water or hydraulic oil, or aspring mechanism 88 such as a coil spring.

For the reinforcing-core 82 to work well, it should be located at leastwithin that portion 58 of the bar 52 that is being bent; if it were toslide within the bar 52 away from that portion 58, it might not provideas good reinforcement. There are a number of ways to prevent suchsliding. One way is to completely fill the bar 52 with thereinforcing-core 82 so that the reinforcing-core 82 cannot slide withinbar 52. This solution can be augmented by sealing the ends of the bar 52so that the reinforcing-core 82 cannot slide out. Another way is to filljust that portion 58 of the bar 52 being bent with the reinforcing-core82 and to seal just that portion 58. Either way, the whole bar 52 orjust the portion 58 being bent can be sealed in any well know way, forexample by inserting a plug 90 or injecting a temporary adhesive orsealing compound that can resist forces applied by the reinforcing-core82 but that can be easily removed after manufacturing has beencompleted.

With reference now to FIGS. 26-36, a method and apparatus for squaringthe bar 52 will be described in further detail. In essence, the priormanufacturing operations, including the bending operation, might haveintroduced in places along the bar 52 a small twist along itslongitudinal axis and/or a small skew of its cross-sectional perimeter,which results could benefit from mitigation.

With reference first to FIGS. 26-30, a squaring apparatus according toone aspect of the invention is generally illustrated at 92. The squaringapparatus 92 has a housing 94 on which are mounted two rollers 96 withsubstantially parallel axes of rotation. Between them, the two rollers96 define a substantially linear feed-path 98. The rollers 96 may definegrooves 100 for improved material handling and adjacent grooves 100 mayin turn define between them a channel 102 having a cross-sectionsubstantially congruent with the cross-sectional perimeter of the bar52. In operation, this channel 102 acts as a die to squeeze the bar 52back into a square and untwisted disposition.

With reference now to FIG. 31, an end portion 58 of the bar 52 can beseen positioned for squaring within the squaring apparatus 92.

With reference now to FIGS. 32-36, the inclusion of a reinforcing-core82 is shown. The reinforcing-core 82 may be the same one as used duringthe bending operation, or else it may be a different one that has beenoptimized for the physical forces and desired results of the squaringoperation.

(b) Operation

With reference to the drawings, the operation of these specificembodiments of the invention will now be described in greater detail.

The manufacturer fabricates or acquires a conventional and substantiallystraight piece of tube-stock having the desired cross-sectional shape,which in the case of this specific example is a tubular bar 52 having arectangular cross-section and sidewalls 56 having a thickness in therange of 0.1 mm to 1 mm.

The manufacturer then inserts into the bar 52 a reinforcing-core 82, forexample a packed mechanical mixture of granules 84, a volume of liquid86, or a spring mechanism 88. The reinforcing-core 82 is placed eitherto extend along the whole length of the bar 52 or else at leastproximate to the portion 58 of the bar 52 being worked on. Once placed,the reinforcing-core 82 is sealed in place with a plug 90 for at leastthe duration of the work.

The manufacturer then configures the bending apparatus 70 to bend aportion of the bar 52 through a desired radius of curvature along itslongitudinal axes, which in the present example is bending the endportion 58 of the bar 52 through the small radius of curvature RS. Toconfigure the bending apparatus 70, one adjusts the size and relativeposition in the plane of the rollers 74 to achieve the desired feed-path76 and channel 80. One might select rollers 74 with grooves 78 thatbetween them define a channel 80 that has a cross-section that issubstantially congruent with the cross-sectional perimeter of thatportion 58 of the bar 52 being bent.

Once the bending apparatus 70 has been configured, the manufacturerdraws the portion 58 to be bent through the channel 80 along thefeed-path 76, allowing the rollers 74 to apply transverse forces to thatportion 58 to urge it to bend through the small radius of curvature RS.

A similar process would be followed to bend the middle portion 62 of thebar 52 through the large radius of curvature RL, and in fact for ease ofmanufacturing that bending operation would likely be performed beforethe operation of tightly bending the end portion 58 of the bar 52through the small radius of curvature RS.

It is possible that during prior manufacturing steps, including bendingoperations, a small cross-sectional skew or longitudinal twist could beintroduced into the bar 52. If so, this result can be mitigated by usingthe squaring apparatus 92.

In preparation for the squaring operation, the manufacturer might eitherleave the reinforcing-core 82 in place within the bar 52 or else mightremove the reinforcing core altogether or else replace it with onehaving different bending and compression characteristics more suitablefor the squaring operation.

The manufacturer then configures the squaring apparatus 92 to square thebar 52 and specifically the portion 58 of the bar 52 that has been bent.To configure the squaring apparatus 92, one adjusts the size andrelative position in the plane of the rollers 96 to achieve the desiredfeed-path 98 and channel 102. One might select rollers 96 with grooves100 that between them define a channel 102 that has a cross-section thatis substantially congruent with the cross-sectional perimeter of theportion 58 of the bar 52 being squared.

Once the squaring apparatus 92 has been configured, the manufacturerdraws the bar 52, and in particular that portion 58 of the bar 52 thathas been bent, through the channel 102 along the feed-path 98, allowingthe rollers 96 to urge against the bar 52 to counteract any longitudinaltwist or cross-sectional skew.

Once the bar 52 has been bent and squared as needed, the manufacturermay remove the plugs 90 and the reinforcing-core 82 for reuse ordisposal, thereby reducing the weight of the bar 52. Alternatively, themanufacturer might chose to keep the reinforcing-core 82 within the bar52, particularly where the reinforcing-core is cheaper and lighter thana solid bar 52 would have been.

The external surfaces 60 of the bar 52 can then be painted or polishedas desired, and the end portions 58 can be sealed for protection or leftopen for drainage, also as desired.

The manufacturer can thus make a set of such bars 52, the bars beingeither identical or varying in shape and size as needed to produce inaggregate a desired shape of grille 50. To assemble the bars 52 into thegrille 50, the manufacturer places the bars 52 in the desiredspace-apart disposition and secures them in their relative position withcrosspieces 54 attached in a conventional manner, for example with aweld, a spot-weld, some adhesive, or a fastener.

Thus, it will be seen from the foregoing examples that there has beendescribed: a method of bending a tube through a desired curvature alongits longitudinal axis; a tube having a desired curvature along itslongitudinal axis made in accordance with this method; an apparatus forbending a tube having a predetermined cross-section through a desiredcurvature along its longitudinal axis; an apparatus for squaring a tubehaving a predetermined cross-section; an apparatus for reinforcing aportion of a tube during manufacturing; a stainless steel tube having adesired curvature along its longitudinal axis, a substantially polygonalcross-section, and a sidewall thickness in a range between one tenth ofone millimeter and one millimeter; and finally a grille assembled from aplurality of such stainless steel tubes in spaced-apart disposition andmeans for connecting adjacent tubes together, including crosspiecesconnected to the tubes by conventional means, including welds,spot-welds, adhesive, or fasteners.

While specific embodiments of the invention have been described andillustrated, such embodiments should be considered as only examples ofthe invention and not as limiting the invention itself, which is to beconstrued in accordance with the accompanying claims.

While the invention has been described as having particular applicationfor grilles, those skilled in the art will recognize it has widerapplication both in the automotive sector and beyond.

1. A method of bending a tube through a desired curvature along itslongitudinal axis, the method comprising: (a) reinforcing a portion thetube with a core that allows the portion to bend but that resistsbuckling of the tube walls; and (b) bending the reinforced portion ofthe tube.
 2. A method as claimed in claim 1, wherein reinforcing aportion of the tube with a core includes inserting into the tube alongitudinally bendable core that resists transverse compression,whereby the core redistributes transverse forces applied to the portion.3. A method as claimed in claim 2, further comprising removing the coreafter bending the reinforced portion of the tube.
 4. A method as claimedin claim 2, wherein reinforcing a portion of the tube with a coreincludes filling the portion with granules.
 5. A method as claimed inclaim 4, wherein filling the portion with granules includes packing theportion with sand.
 6. A method as claimed in claim 2, whereinreinforcing a portion of the tube with a core includes the portion withliquid.
 7. A method as claimed in claim 2, wherein reinforcing theportion of the tube with a core includes inserting into the portion asprung mechanism that inscribes the portion.
 8. A method as claimed inclaim 7, wherein reinforcing the portion of the tube with a coreincludes inserting into the portion a coil spring that has an outsideperimeter substantially congruent with the inside perimeter of theportion.
 9. A method as claimed in claim 2, wherein reinforcing aportion of the tube with a core includes sealing at least one end of theportion to discourage the core from coming out of the portion.
 10. Amethod of bending a tube as claimed in claim 2, wherein a cross-sectionof the tube is polygonal.
 11. A method as claimed in claim 10, whereinthe cross-section of the tube forms a quadrilateral.
 12. A method asclaimed in claim 11, wherein the tube is formed from metal.
 13. A methodas claimed in claim 12, wherein the tube is formed from stainless steel.14. A method as claimed in claim 13, wherein the thickness of the tubesidewall is in a range between one tenth of one millimeter and onemillimeter.
 15. A method as claimed in claim 14, wherein the thicknessof the tube sidewall is in a range between one tenth of one millimeterand five tenths of one millimeter.
 16. A method as claimed in claim 15,wherein the thickness of the tube sidewall is one tenth of onemillimeter.
 17. A method as claimed in claim 2, wherein bending thereinforced portion of the tube includes rolling the portion betweenrollers that define between them a path having the desired curvature.18. A method as claimed in claim 17, wherein rolling the portion betweenrollers that define between them a path having the desired curvatureincludes feeding the portion through a channel defined between therollers that is substantially congruent with the outside perimeter ofthe portion.
 19. A method as claimed in claim 18, further comprisingsquaring the tube, wherein squaring includes at least one of: (a)squaring the cross-section of the portion; and (b) longitudinallyuntwisting the portion.
 20. A method as claimed in claim 19, whereinsquaring the tube includes rolling the tube between rollers that definebetween them a substantially straight path.
 21. A method as claimed inclaim 20, wherein rolling the tube between rollers that define betweenthem a substantially straight path includes feeding the portion througha channel defined between the rollers that is substantially congruentwith the outside perimeter of the tube.
 22. A tube having a desiredcurvature along its longitudinal axis made in accordance with the methodof claim
 1. 23. A tube as claimed in claim 22, further made inaccordance with the method of claim
 2. 24. A tube as claimed in claim23, further made in accordance with the method of claim
 3. 25. A tube asclaimed in claim 23, further made in accordance with the method of claim4.
 26. A tube as claimed in claim 25, further made in accordance withthe method of claim
 5. 27. A tube as claimed in claim 23, further madein accordance with the method of claim
 6. 28. A tube as claimed in claim23, further made in accordance with the method of claim
 7. 29. A tube asclaimed in claim 28, further made in accordance with the method of claim8.
 30. A tube as claimed in claim 23, further made in accordance withthe method of claim
 9. 31. A tube as claimed in claim 23, further madein accordance with the method of claim
 10. 32. A tube as claimed inclaim 31, further made in accordance with the method of claim
 11. 33. Atube as claimed in claim 32, further made in accordance with the methodof claim
 12. 34. A tube as claimed in claim 33, further made inaccordance with the method of claim
 13. 35. A tube as claimed in claim34, further made in accordance with the method of claim
 14. 36. A tubeas claimed in claim 35, further made in accordance with the method ofclaim
 15. 37. A tube as claimed in claim 36, further made in accordancewith the method of claim
 16. 38. A tube as claimed in claim 23, furthermade in accordance with the method of claim
 17. 39. A tube as claimed inclaim 38, further made in accordance with the method of claim
 18. 40. Atube as claimed in claim 39, further made in accordance with the methodof claim
 19. 41. A tube as claimed in claim 40, further made inaccordance with the method of claim
 20. 42. A tube as claimed in claim41, further made in accordance with the method of claim
 21. 43. Anapparatus for bending an elongated body having a predeterminedcross-section through a desired curvature along its longitudinal axis,comprising: (a) a housing; (b) first, second, and third rollers, eachroller respectively having an axis of rotation and a rolling surface,the rollers being rotatably mounted on the housing such that: (i) theirrespective axes of rotation are substantially parallel; and (ii) theirrespective rolling surfaces define between them a channel having thedesired curvature and a cross-section substantially congruent with thecross-section of the body.
 44. An apparatus for squaring an elongatedbody having a predetermined cross-section, comprising: (a) a housing;(b) first and second rollers, each roller respectively having an axis ofrotation and a rolling surface, the rollers being rotatably mounted onthe housing such that: (i) their respective axes of rotation aresubstantially parallel; and (ii) their respective rolling surfacesdefine between them a channel having a cross-section substantiallycongruent with the cross-section of the body.
 45. An apparatus forreinforcing a portion of a tube during manufacturing, comprising a corehaving an outer diameter substantially equal to the inner diameter ofthe tube that allows the portion to bend along its longitudinal axis butthat resists buckling of the sidewalls of the portion.
 46. An apparatusas claimed in claim 45, wherein the core is longitudinally bendable andresists transverse compression, whereby it is operable to redistributetransverse forces applied to the portion.
 47. An apparatus as claimed inclaim 46, wherein the core includes a plurality of granules.
 48. Anapparatus as claimed in claim 47, wherein the granules include sand. 49.An apparatus as claimed in claim 46, wherein the core includes liquid.50. An apparatus as claimed in claim 46, wherein the core includesspring mechanism that inscribes the portion.
 51. An apparatus as claimedin claim 50, wherein the spring mechanism is a coil spring having anoutside perimeter substantially congruent with the inside perimeter ofthe portion.
 52. A stainless steel tube having a desired curvature alongits longitudinal axis, a substantially polygonal cross-section and asidewall thickness in a range between one tenth of one millimeter andone millimeter.
 53. A tube as claimed in claim 52, wherein the sidewallthickness is in a range between one tenth of one millimeter and fivetenths of one millimeter.
 54. A tube as claimed in claim 53, wherein thesidewall thickness is one tenth of one millimeter.
 55. A tube as claimedin claim 52, wherein the stainless steel alloy is iron-chromium-nickelalloy
 304. 56. A grille, comprising: (a) a plurality of stainless steeltubes as claimed in claim 52, in spaced-apart disposition; and (b) meansfor connecting adjacent tubes.